The mechanism of acuity reduction, and the site of involvement of naturally occurring amblyopia in humans is not well understood. The proposed research represents detailed investigations of spatial and temporal characteristics of the amblyopic visual system at different levels in the visual pathways via psychophysical and electrophysiological techniques. The goals of the research are to better understand the neural mechanisms of amblyopia in humans, and to develop improved methods of diagnosis and treatment through the application of psychophysical and physiological optics techniques.